Conventionally, a semiconductor module has been attached to a heat sink by interposing grease therebetween in order to achieve improvements in bondability and heat releasability. In such a case, the semiconductor module is attached to the heat sink by using a pressing plate and screws in order to achieve warpage inhibition and to ensure intimate contact with grease. For example, a technique to fix a semiconductor module by providing a through hole in a central portion of a semiconductor module, passing a screw through the through hole and pressing the semiconductor module with a dish spring plate (see Patent Literature 1).
A heat sink is ordinarily attached to a cooling jacket by using screws. For example, a semiconductor module has been disclosed in which an insulating substrate is soldered to a heat sink; a semiconductor chip is fixed on the insulating substrate; and a case is bonded to a peripheral portion of the heat sink (see Patent Literature 2).